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This invention is directed to certain compositions of matter including multi-arm star polymers derived from silicon containing dendrimers in which the arms of the resulting star polymer contain in their molecule the characteristic moiety 
where each Rxe2x80x2 can be the same or different and is an alkyl group containing 1-6 carbon atoms such as methyl and ethyl or an aryl group such as phenyl; Rxe2x80x3 is alkylene radical xe2x80x94(CH2)axe2x80x94 in which a has a value of 2 or 3; and Rxe2x80x2xe2x80x3 is the xe2x80x94(CH2)bCH3 group in which b has a value of 1-50. The invention is also directed to the use of such compositions of matter, and the use of multi-arm star polymers derived from amine or imine terminated dendrimers which have been epoxidized with monofunctional glycidoxy organosilicon compositions, for dissolving metals and other electrophiles.
While U.S. Pat. No. 5,902,863 (May 11, 1999) and U.S. Pat. No. 5,938,934 (Aug. 17, 1999) describe networks containing dendrimers having in their molecule groups at the outer surface containing the moiety 
these prior art patents do not describe any dendrimers containing the moiety 
where Rxe2x80x2, Rxe2x80x3, and Rxe2x80x2xe2x80x3 have the same meaning as defined above.
This is a significant distinction since the prior art compositions containing an xe2x80x94SH moiety are inherently very reactive, possess an odor of rotten eggs, and are very unstable when exposed to open environment. In contrast, compositions of this invention containing the xe2x80x94SRxe2x80x2xe2x80x3 moiety are inherently non-reactive, possess no odor, and are very stable when exposed to open environment. In addition, prior art compositions containing the xe2x80x94SH moiety have very limited use, i.e., for preparing networks or other dendrimers; whereas compositions of the invention containing the xe2x80x94SRxe2x80x2xe2x80x3 moiety have a variety of uses as discussed hereafter.
While U.S. Pat. No. 5,739,218 (Apr. 14, 1999) describes certain dendrimer compositions obtained by epoxidation of amine or imine terminated dendrimers, it does not suggest use of the resulting dendrimers for dissolving metals and other electrophiles. Such a use cannot be inferred from a consideration of U.S. Pat. No. 5,938,934, since the ""934 patent relates specifically to the use of networks prepared from such dendrimers, rather than to the use of the dendrimer composition itself which is not a network. This is a significant distinction when one considers that networks of dendrimers, i.e., crosslinked molecules, are generally insoluble in all solvents, whereas the non-crosslinked dendrimers themselves are generally soluble in many solvents.
Lastly, dendrimers and star polymers according to this invention should not be confused with dendrimers and star polymers described in U.S. Pat. No. 5,387,617 (Feb. 7, 1995) and U.S. Pat. No. 5,560,929 (Oct. 1, 1996), since the hydrophobic tail used to cap dendrimers and star polymers in the ""617 and ""929 patents does not contain silicon atoms. Rather, the capping materials used in the ""617 and ""929 patents are hydrocarbon chlorides and bromides such as cetyl bromide or xcex1,xcex2-epoxides derived from epoxidation of terminal olefins such as 1,2-epoxydecane.
This invention is directed to multi-arm star polymers containing a hydrophilic dendritic core and hydrophobic silicon containing arms. The number of arms per molecule is dependent upon the functionality of the dendrimer precursor used in its synthesis, and the degree of conversion achieved during the synthesis. Depending upon the density of functionality, i.e., the generation of the dendrimer precursor used in the synthesis, the number of arms may range from 3 to several thousand, but generally the number of arms will range between 3-4,000, preferably 4-300.
Dendrimer precursors suitable for use in the manufacture of these multi-arm star polymers may consist of a polyamidoamine (PAMAM), polypropyleneimine (PPI), poly(amidoamine-organosilicon) (PAMAMOS), or poly(propyleneimine-organosilicon) (PPIOS), dendrimer. Each of the arms of the multi-arm star polymers contain silicon, and the number of silicon atoms in each of the arms of the star polymer can vary from a single silicon atom to as many as about 30 silicon atoms.
In general, these multi-arm star polymers can be prepared by two different synthetic processes. A first method involves a thiol addition to the unsaturated groups of a dendrimer containing silicon atoms, in the presence of a catalyst such as 2,2xe2x80x2-azobisisobutyronitrile (AIBN); while a second method involves epoxidation of an amine or imine terminated dendrimer using a monofunctional glycidoxypolysiloxane, i.e., a monoepoxypropoxy functional polysiloxane.
It has been found that these multi-arm star polymers evidence properties enabling their use in several different and unusual applications, including their use as (i) surface active phase transfer agents, (ii) solubilizers for inorganic cations, metal atoms, and nanoscopic clusters in hostile organic environments, (iii) macromolecular hosts for complexing and encapsulating electrophiles, (iv) catalysis, (v) molecular sensors, (vi) harvesting of metals from aqueous salt solutions, (vi) harvesting of residual polymerization catalysts or initiators from organosilicon polymers, and (vii) compatibilization of organosilicon polymers and rubbers with various inorganic, organic, or organometallic electrophiles.
In particular, their use as phase transfer agents (i) and solubilizers (ii) was demonstrated by a transport of copper Cu2+ cations from an aqueous medium into an organic medium, and their dissolution and retention in the dissolved state; as well as the formation, dissolution, and retention of copper Cu0 metal, in an organic solvent, which represents hostile environments for such species.
As used herein, the term electrophile is intended to mean and includes (i) metal cations, (ii) metal salts, (iii) metal oxides, (iv) elemental metals, (v) water soluble organic molecules, and (vi) water soluble organometallic molecules. Some representative metal cations are Cu1+, Cu2+, Fe2+, Fe3+, Au3+, Ag+, Pt3+, Rh3+, Ni2+, Co2+, and Cd2+. Some representative elemental metals are Au0, Ag0, Co0, Cu0, Ni0, or Pt0. Some representative water soluble organic molecules and water soluble organometallic molecules are pigments, dyes, indicators, light sensitizers, radiation sensitizers, catalysts, electro-conductive materials, magnetic materials, non-linear optical materials, liquid crystalline materials, light emitting materials, fluorescent materials, phosphorescent materials, polymerizable monomers, polymerization initiating materials, biomedical materials, pharmaceutical products, biologically active materials, biologically inactive materials, antiseptic materials, and surface active agents. Some particular representative water soluble organic molecules are C37H27N3O3xc2x72NaSO3 (methylene blue) and C15H15N3O2 (methyl red).
These and other features of the invention will become apparent from a consideration of the detailed description.